Thermosensitive colouring materials



- THERMOSENSITIVE OLOURING MATERIAL Frederick George Francis, OldSouthgate, London, and 'fJohniAlbert ,Seaward, Enfield, England,assiguors to Caribonum ll'imitemLondon, England, a British com '2 1:10'DraWiBg'.'- Filed May 7,1958, Ser. No. 733,469 Cla1ms-pr10rity, appliation Gre'at Britain May 16, 1 957- 1; .f'. 1(Cl.. 106-1-2'3)presentinvention relatesjtocolouring materials and is-concernedparticularly, but not exclusively, with colouring materials employed inthe manufacture of inks, typewriter and other inked ribbons and carbonpapers.

Copying processesare 'known, which make use of thermo-sensitive paper orother sheet material. In such processes, 'a sheet of thermo-sensitivematerial, such as a sheet of paper; coated with one or, more layers of athermo sensitive composition which produces a distinctive colouration inthose areas; subjected to a suitable increase in temperature, is placedin contact with and above the printed, typewritten or other material tobe copied and the sheets, are then irradiated with infra-red rays. Thisgenerates a heat pattern inv the copy sheet in accordance with thecharacters or other markings on the material to 2,992,121 2 PatentedJuly 11,1961

matic-coloured, isused hereinafterand. in the appended claims to meansuch. coloured, non-blackpigments or othercolouring materials.

gAcoording to the invention, a chromatic-coloured ink composition isprovided,-.which is adapted to produce coloured written copy mattercapable of'being copied by a thermosensitive copyingprocess, which inkcomposition consists essentially .of an oil-containing vehicle, at leastone chromatic-coloured colouring material in an amount of from 15% to30% by weight of the ink composition and finely-divided antimony in anamount sufficient to give "satisfactory thermosensitive copy byimparting infrared absorptive properties to the ink composition withoutthe antimony being'presjent in an -amount sufliciently large to 'obscurethe chromatic colour of the] ink composition.

The colouring material ink composition of the present invention may beembodiedin'sor used as printing or other'inks, or may be used toimpregnate typewriter and other inked ribbons or may be incorporated ina transferable. composition usedinthe manufacture of carbon paper andother. transfer sheet material.

be copiedend this heat pattern-develops'the copy sheet byproducing thecolouration in the thermo-sensitive composition thereof to produce'acopy of the original material. In general, the infra-red rays aredirected on to the material to be copied'through the copy sheet, whichis not itself absorbentof infra-red radiation.

' It has been found that, generally speaking, satisfactorycopiescan beobtained by such processes only from black writings, drawings or typingsand black pencil writings and that it is'virtually impossible to operatea thermosensitive copying process'with coloured material. This method ofcopying is therefore not normally feasible with material which is partlyin black and partly in a colour, e.g. red. Good copies can be obtained,however, from typed material produced by means of a black typewriterribbon, which is impregnated with an which contains carbon black. Redtypewriter ribbons and other coloured ribbons, such as purple, green andblue, are almost completely unsatisfactory from the'standpoint ofobtaining copiesbyfmeans of ther fno-sensitive copying paper frommaterial typed with them. Depending upon the colouring' material used,brown ribbons will sometimes produce matter which can be 'copiedin' thisway, particularly if the brown colouring material in the typewriterribbon ink is obtained by the addition 'of carbon black to anothercolouring matter, such as a red pigment.

In order to overcome this defectof coloured material, it has beenproposed to add graphite'in a very high proportion in respect of theother coloured pigmentary matter used in the manufacture oftypewriterribbon ink. German Gebrauchsmuster No, 1,734,641 refers to theuse of a "small quantity of graphite for this 'purpose, butit has notbeen found possible to obtain any useful results unless large quantitiesare employed. This is the principal disadvantage of graphite for thispurpose, since the high proportion necessary to incorporate sufficientblack into the colouring material to enable writings produced with it tobe absorbent of infra-red radiation renders the writings so dull incharacter as to be unsatisfactory for ordinary purposes.

It is therefore an object of the present invention to provide acoloured, i.e. non-black, colouring material which overcomes the defectsof ordinary colouring materials in respect of thermo-sensitive copyingprocesses and also avoids the disadvantages attendant upongraphitecontaining colouring materials. The expression chro- .Ithasbeenfound that fairly large quantities of powdered or otherwisefinely-divided antimony are generally required to give satisfactoryresults, but the colour of the other pigmentary or colouring matter usedin the colouring. material. is not adversely affected and very goodresults can be obtained in producing written matter by printing,writing, typing or by using carbon paper. The actual quantity ofantimony required to give the best results, as regards the quality ofcopies produced from the ,written matter ;by*means of a thermo-sensitivecopy paper, depends to some extent upon'the colour and nature of thepigment or pigments, but in general it has been found satisfactory toemploy the powdered antimony inan' amount of 15 to 25% by weight of theink, the latter preferably containing 15 to 30% by weight of lake colouror other pigment or coloured material.

Commercial antimony can be readily powdered and can be'mixe'dand groundwith the other ingredients of theink or other colouring material as ifit were a pig- In entself it is carefully ground, such as on a tripleroll mill, antimony can be obtained in an extremely finelydividedcondition. 'If such an ink is used to impregnate a typewriter ribbon,the material produced by typing with the ribbon is found to be a betterand much-brighter colour than that obtained with a graphite-containingink ribbon. Y.

In order that the invention may be readily understood, the followingspecific examples are given.

Example 1 Parts by weight Lardoil 29 Light mineral oil 31.5Triethanolamine oleate i p, b 2.4 Strong Violet Lake 20. Antimony 16.6

Example 2 Castor oil 41.7 Lard oil 10.4 Light mineral oil 14.0 StrongRed Lake 13.0 Dark Red Lake 3.5 Anti-oxidant 1 0.8 Antimony 16.6

1 Nonoxol D.C.P.

3 2 Example 3 Lard oil 26.5 Light mineral oil 29.5 Triethanolamineoleate 2.2 Strong Blue Lake 25.0 Antimony 16.7

Example 4 Light mineral oil 62.5 Strong Deep Green Lake 20.8 Antimony16.7

The foregoing examples set out compositions suitable for use as inks,which can be used as such or used to impregnate typewriter or otherribbons. The following Example 5 sets out a formulation for thetransferable coating of a carbon paper.

Example 5 Parts by weight The colour of the particular lake is chosen tosuit the desired colour of the carbon paper dope, from the Strong VioletLake, Strong Red Lake, Dark Red Lake, Strong Blue Lalze land Strong DeepGreen Lake mentioned in Examples 1 o a ove.

We claim:

1. A coloured ink composition which is adapted to produce colouredwritten copy matter capable of being copied by a thermo-sensitivecopying process, which ink composition consists essentially of anoil-containing vehicle, at least one chromatic-coloured colouringmaterial in an amount of from 15% to 30% by weight of the inkcomposition and finely-divided antimony in an amount sufficient to givesatisfactory thermosensitive copy by imparting infra-red absorptiveproperties to the ink composition without the antimony being present inan amount sufiiciently large to obscure the chromatic colour of the inkcomposition.

2. A violet-coloured ink composition according to claim 1, whichconsists in parts by weight of 29 parts of lard oil, 31.5 parts of lightmineral oil, 2.4 parts of triethanolamine oleate, 20.5 parts of StrongViolet Lake and 16.6 parts of finely-divided antimony.

3. A red-coloured ink composition according to claim 1, which consistsin parts by weight of 41.7 parts of castor oil, 10.4 parts of lard oil,14.0 parts of light mineral oil, 13.0 parts of Strong Red Lake, 3.5parts of Dark Red Lake, 0.8 part of antioxidant and 16.6 parts offinelydivided antimony.

4. A blue-coloured ink composition according to claim 1, which consistsin parts by weight of 26.5 parts of lard oil, 29.5 parts of lightmineral oil, 2.2 parts of triethanolamine oleate, 25.0 parts of StrongBlue Lake and 16.7 parts of finely-divided antimony.

5. A green-coloured ink composition according to claim 1, which consistsin parts by weight of 62.5 parts of light mineral oil, 20.8 parts ofStrong Deep Green Lake and 16.7 parts of finely-divided antimony.

6. A coloured transfer sheet material which is adapted to producecoloured written copy matter capable of being copied by athermo-sensitive copying process, which consists of a paper web carryinga transferable coloured ink composition consisting essentially of anoil-containing vehicle, at least one chromatic-coloured colouringmaterial in an amount of from 15% to 30% by weight of the inkcomposition and finely-divided antimony in an amount of from 15 %to 25%by weight of the ink composition, the antimony thereby being present inan amount sufi'icient to give satisfactory thermosensitive copy byimparting infra-red absorptive properties to the ink composition withoutobscuring the chromatic colour of the ink composition.

7. The coloured transfer sheet material of claim 6 in which thetransferable coloured ink composition consists, in parts by weight of,12.2 parts of fatty grey carnauba wax, 11.9 parts of ceresin wax and30.7 parts of mineral oil as the oil-containing vehicle, 27.7 parts of aStrong Lake colour selected from the group consisting of Strong VioletLake, Strong Red Lake, Dark Red Lake, Strong Blue Lake and Strong DeepGreen Lake and 17.5 parts of finely-divided antimony.

8. A coloured inked ribbon adapted to produce coloured written copymatter capable of being copied by a thermosensitive copying process,which consists of a ribbon impregnated with a coloured ink compositionconsisting essentially of an oil-containing vehicle, at least onechromatic-coloured colouring material in an amount of from 15% to 30% byweight of the ink composition and finely-divided antimony in an amountof from 15% to 25% of the ink composition, the antimony thereby beingpresent inan amount suflicient to give satisfactory thermosensitive copyby imparting infra-red absorptive properties to the ink compositionwithout obscuring the chromatic colour of the ink composition.

References. Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Murmann: Zeitschrift-fiir Physik, vol. 54, March 1929 (pages746-748).

Koller: General Electric Review, Infra-Red, March 1941 (pages 167-173).

Mitchell: The Analyst (1935), vol. (pages 454-61).

1. A COLOURED INK COMPOSITION WHICH IS ADAPTED TO PRODUCE COLOUREDWRITTEN COPY MATTER CAPABLE OF BEING COPIED BY A THERMO-SENSITIVECOPYING PROCESS, WHICH INK COMPOSITION CONSISTS ESSENTIALLY OF ANOIL-CONTAINING VEHICLE, AT LEAST ONE CHROMATIC-COLOURED COLOURINGMATERIAL IN AN AMOUNT OF FROM 15% TO 30% BY WEIGHT OF THE INKCOMPOSITION AND FINELY-DIVIDED ANTIMONY IN AN AMOUNT SUFFICIENT TO GIVESATISFACTORY THERMOSENSITIVE COPY BY IMPARTING INFRA-RED ABSORPTIVEPROPERTIES TO THE INK COMPOSITION WITHOUT THE ANTIMONY BEING PRESENT INAN AMOUNT SUFFICIENTLY LARGE TO OBSCURE THE CHROMATIC COLOUR OF THE INKCOMPOSITION.